Carburetor



Patented July 27, 1926.

UNITED STATES PATENT OFFICE...

ALFRED C. STEWART, OF LOS ANGELES, CALIFORNIA.

Y CARBURETOR.

Application filed April 14, 1920. Serial No. 373,819.

Fig. 1 is a vertical section of the carburetor with an attached float chamber shown partly in elevation;

Fig. 2 is a section on line 2-2 in Fig. 1;

Fig. 3 is a side elevation of the carburetor and the connection therefrom to the engine.

The carburetor constituting my invention comprises a casing 1 formed with a mixing chamber 2 having an air inlet 3 at its bottom and a mixture outlet 4 at one side. An air valve5 is mounted to control the air inlet 3, 'said air valve being carried by a vertical stem 6 sliding in a vertical guideway 7 formed in an upward extension 7 of casing 1 and said valve tending to move to closed position by its own weight and being adapted to be lifted by pressure of the air at the air inlet to open the air inlet. Saidair valve is provided with a cylindrical wall 8 extending upwardly therefrom and working within a cylindrical chamber 9 in the casing 1 above the mixing chamber. The stem 6 of the air valve is hollow and is provided at itsupper end with a passage 10 for communication 0 fuel thereto from a chamber 11 formed at the top of the upward extension 7 of the casing 1. Said chamber 11 is closed at the top by plug 12 carrying an adjustable screw 13 at the lower end of which is mounted by a pivot 14 a fuel valve 15 which passes through the opening 10' aforesaid and tapers upwardly so as to tend to open the passage between the walls of said opening and the said fuel valve as the valve stem 6 is raised. By adjustment of the screw 13 the amount of fuel admitted is properly controlled according to the general requirements of the engine to which the device is connected; the fuel ad mission being, however, further controlled, according to the momentary requirements 0 the engine while running, by the resultin variations in position of the air valve an the fuel inlet opening 10 at the upper end thereof, relatively to the fuel valve member '15, and by the variations in pressure in thecontrolling chamber and at the air inlet. The chamber 11 communicates with any suitable source of fuel supply, for example, with a fuel conduit 16 leading to a float chamber or fuel chamber 17. The lower end of the core 18 in valve stem 6 communicates with passages 19 extending therefrom to the topof the air valve 5 and passages 20 lead from the top of the air valve downwardly through the air valve and open on the lower face of the air valve. to supply the fuel with A incoming air. One or more other passages 22 may be provided leading from the top of: vthe air valve to the mixing chamber, said passages 22 establishing permanent and substantially invariable restricted communication between the controlling chamber and the intake of the engine. The air valve 5 is preferably formed with a conical lower face and directly above the portion thereof which seats on the air inlet 3 with a downwardly flaring shoulder portion 23, the passages 22 opening into the mixing chamber directly above this shoulder portion. The pressure within the controlling chamber 9 is controlled by a valve member 25 pivotally mounted .at 26 on the casing 1 and having a port 27 communicating with the outer air and adapted to move into and out of register with the passage 28 leading to the interior of chamber 9. Valve 25 is connected to a controlling rod 30, or other device for manual operation thereof, the operation of this valve taking the place of the usual operf ation of the throttle for the carburetor.

In the operation of the carburetor, the suction from the engine tends to maintain a condition of partial vacuum in the mixing chamber 2, which is in direct and permanently unobstructed communication withthe.

intake or manifold 11 of the engine 32, as indicated in Fig. .3, the usual throttle bein omitted. In starting, the valve 25 is close and the condition of partial vacuum is adually communicated to the controlling 0 amber 9 by passage of air through the restricted openings 22.- The air valve 5 is gradually raised y reason of the decrease in air pressure on its upper face due to the partial vacuum in chamber 9, part 8 acting as a pisf ton in said chamber, and at the same time the fuel valve opening 10 is opened by raising of the valve stem, and fuel is drawn or forced up from the fuel chamber and past the conical valve plug or metering pin 1 5, due to the difference between the pressure in the fuel chamber and in, the controlling chamber, the amount of fuel thus admitte to the controlling chamber thus increasing in correspondence with the admission of air through the valve opening 10, by reason of the increase in the dlfi'erence of pressure between the fuel chamber and the controlling chamber. The air valve rises gradually being controlled by the gradual sucking of air from the controlling chamber through passages 22, so that a gradual increase in air admission is effected in starting. If full power is desired, valve 25 is left closed so that full lifting effect is exerted on the air valve and sufficient air is admitted by full opening of the valve and at the same time the fuel is supplied in suflicient quantity to give a rich-mixture. In running light and at full s eed the valve 25 is opened so as to reduce t e condition of partial vacuum in chamber 9, allowing the air valve to descend so as to decrease the amount of air admitted but decreasing the fuel supply in greater proportion by reason of the increase in the pressure in chamber 9, together with the decrease in the opening of the fuel valve. A weak or poor mixture is thus produced giving high fuel efficiency under conditions of low load. In idling or running under minimum load the valve 25 is opened still more to provide a mixture supply of minimum quantity and richness.

All the functions of a carburetor provided with the usual throttle between the carbure- V tor and the engine can therefore be effected by the carburetor above described without any throttling action on the mixture as it passes from the carburetor to the engine, thereby preventing separation of fuel from the mixture by reason of the obstruction presented by a throttle and ensuring that the mixture reaches the engine in most effective condition.

What I claim is:

1. In combination with the intake of an internal combustion engine, a carburetor comprising a mixing chamber in permanently unobstructed communication with said intake, valve means for regulating the trolling chamber so as to permit fuel to be forced therethrough due to the difference between the pressure in said fuel chamber and in said controlling chamber, valve means in said fuel passage, a second fuel passage leading from said controlling chamber to said first-named valve means, means between the air inlet and the controlling chamber and responsive to the difference in pressure therebetween and adapted to open said firstnamed valve means and to also open said valve means in the fuel passage, in proportion to said difference in pressure, and a manually controlled valve controlling communication between said controlling chamber and the atmosphere.

2. In combination with tl1e intake of an internal combustion engine a carburetor comprising an air inlet, an air valve constituting the sole means of air passage control between said air inlet and said intake and tending to move to closed position, a controlling chamber in invariable restricted communication with said intake, a fuel chamber, a fuel passage leading from said fuel chamber to said controlling chamber so as to permit fuel to be forced there'through due to the difference between the pressure in said 'fuel chamber and in said controlling chamber, additional fuel passage means leading from said controlling chamber to the path of the air between said air inlet and said intake, a fuel valve in said first-named fuel'passage, means responsive to the difference between the pressure in said air inlet and in said controlling chamber and adapted to open said air valve and said fuel valve under the influence of andin proportion to said difference in pressure, an air passage leading from said controlling chamber to the outer air, anda manually controlled valve in said last-named air passage.

In testimony whereof I have hereunto subscribed my name this 30thday of March, 1920.

ALFRED o. STEWART, 

